Motorized bone cement mixing and delivery system with a flexible delivery extension tube and enlarged connector for delivering cement into living tissue

ABSTRACT

A bone cement mixing and delivery system including a mixer, a delivery device, and a flexible extension tube. A connector is attached to a distal end of the flexible tube. The connector includes a housing, a spindle configured with a fitting, and an enlarged knob. The spindle is seated within the housing and is configured to rotate between a closed and open position. In the open position, the spindle allows flow from the delivery device flexible extension tube into a bore of the spindle and into the spindle fitting. A delivery cement cannula is attached to the spindle fitting for allowing cement to travel from the delivery tube into living tissue. The enlarged knob is used to rotate the spindle from an open to a closed state and vice versa.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/961,216, filed 6 Dec. 2010, now U.S. patent Ser. No. ______.application Ser. No. 12/961,216 is a divisional of U.S. patentapplication Ser. No. 12/652,295, filed 5 Jan. 2010, now U.S. Pat. No.7,854,543. application Ser. No. 12/652,295 is a continuation of U.S.patent application Ser. No. 12/416,171, filed 1 Apr. 2009, now U.S. Pat.No. 7,658,537. application Ser. No. 12/416,171 is a continuationapplication of PCT Application No. PCT/US2007/021408, filed 5 Oct. 2007,which claims priority to U.S. Provisional Patent Application Ser. No.60/828,509, filed 6 Oct. 2006 and U.S. Provisional Patent ApplicationSer. No. 60/969,173, filed 31 Aug. 2007. Each of the above-listedpriority applications are hereby incorporated by reference in theirentirety.

FIELD OF INVENTION

The present invention is generally related to bone cement mixing anddelivery systems in which separate components of bone cement are mixedtogether in a mixer to form a bone cement mixture. The mixture istransferred to a delivery device and then delivered to a target site,such as a vertebral body or other anatomical site.

BACKGROUND OF THE INVENTION

Bone cement mixing and delivery systems are well known for mixingseparate components of bone cement together to form a uniform bonecement mixture and then delivering that mixture to a target site.Typically, such systems employ a mixer having a handle for manuallymixing the components. Once mixed, the mixture is then manuallytransferred to a delivery device such as a syringe. The syringe is usedto inject the mixture into the target site. Examples of target sitesinclude medullary canals for total hip arthroplasty procedures,vertebral bodies for vertebroplasty or kyphoplasty procedures, and othersites in which bone cement is required.

Often, the types of bone cements used in these procedures have shortworking time windows of only a few minutes thereby affecting the amountof time available for mixing and delivering the mixture to the targetsite. Current systems require a great deal of user interaction inset-up, including manually mixing the bone cement components andmanually transferring the mixture to the delivery device. This userinteraction delays delivery of the mixture to the target site, whilealso exhausting the user's energy. As a result, there is a need for bonecement mixing and delivery systems that are capable of quick set-up,with little user interaction.

One example of a bone cement mixing and delivery system that attempts toimprove set-up time is shown in U.S. Pat. No. 5,571,282 to Earle. Earlediscloses a motorized mixer that is used to mix the bone cementcomponents. The mixer mixes the components a pre-selected amount oftime, as set by the user. At the end of the pre-selected time, the mixerstops automatically and pressure is applied to the mixture to push themixture out through a port in the bottom of the mixer to a syringe or adelivery cartridge.

The release of odors and gases associated with the bone cementcomponents during mixing can also be undesirable. As a result, there isalso a need for bone cement mixing and delivery systems that aresubstantially self-contained such that the odors and gases associatedwith the components are not substantially released during mixing ortransfer.

One example of a bone cement mixing and delivery system that providessome containment is shown in U.S. Pat. No. 5,193,907 to Faccioli et al.Faccioli et al. discloses an apparatus for mixing and delivering bonecement formed from liquid and powder components. The apparatus comprisesa cylindrical body and a plunger slidable within the body. A powderchamber stores the powder component between the plunger and a distal endof the body. A glass ampoule stores the liquid component inside theplunger. To mix the components, a user presses a plug in the plunger'sproximal end to urge a tip of the glass ampoule against a cammed surface(or against a piercing member) to release the liquid component. Theliquid component then passes through channels defined in the plunger'shead to the powder chamber. The liquid and powder are mixed by shakingthe body to form the bone cement mixture. After mixing, the plunger ispressed to discharge the bone cement mixture out of an exit port in thebody and through a flexible conduit to a target site.

These prior art systems are suitable for reducing set-up times,conserving a user's energy, and reducing exposure of the user to thebone cement components. However, there is still a need in the art forbone cement mixing and delivery systems that are capable of furtherreducing set-up time and enabling quick operation to deliver bone cementto a target site.

SUMMARY OF THE INVENTION

The present invention provides a bone cement mixing and delivery system.The system comprises a mixer for mixing components to form a bone cementmixture and a delivery device for receiving the bone cement mixture fromthe mixer and for delivering the mixture to a target site. The mixerincludes a housing defining a mixing chamber for receiving thecomponents of bone cement. The delivery device includes a reservoirdefining a delivery chamber in communication with the mixing chamber forreceiving the mixture from the mixing chamber. The mixer furtherincludes a mixing paddle disposed in the mixing chamber for mixing thecomponents to form the mixture. A mixing shaft engages the mixingpaddle. A transfer mechanism transfers the mixture out from the mixingchamber and into the delivery chamber. A motor operatively engages boththe mixing shaft and the transfer mechanism. The motor operates torotate the mixing shaft and mix the components in the mixing chamber fora predetermined mixing time to form the mixture. The motor also operatesto actuate the transfer mechanism to automatically transfer the mixturefrom the mixing chamber to the delivery chamber after the predeterminedmixing time has elapsed.

A method of mixing and transferring the components is also provided. Themethod includes disposing the components in the mixing chamber of themixer with the mixing paddle. The motor is started to actuate the mixingshaft and move the mixing paddle in the mixing chamber to mix thecomponents for a predetermined mixing time. After the predeterminedmixing time elapses, operation of the motor continues to actuate thetransfer mechanism. A predetermined amount of the mixture isautomatically transferred from the mixing chamber to the deliverychamber after the predetermined mixing time has elapsed and in responseto actuating the transfer mechanism.

The system and method of the present invention have the advantage ofusing the same motor to actuate both the mixing paddle and the transfermechanism to minimize weight, cost, and waste, especially consideringthat the system is preferably intended for single use. Furthermore, thesystem and method of the present invention reduce user interactioncompared to prior art devices and increases the readiness in which anoperator can prepare a batch of bone cement for surgical purposes. Thisis useful when the bone cement increases in viscosity quickly and has ashort working window.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features and advantages of this invention willbe apparent from the following detailed description of the preferredembodiment and accompanying drawings in which:

FIG. 1 is a top perspective view of a bone cement mixing and deliverysystem including a mixer and a delivery device;

FIG. 2 is a side elevational view of the system of FIG. 1;

FIG. 3 is a top view of the system of FIG. 1;

FIG. 4 is a partial front perspective view of the system with a casingand middle housing portion removed to show a motor and transfermechanism of the mixer;

FIG. 5 is a partial top perspective view of a bottom housing portion ofthe mixer showing a switch and gears of the transfer mechanism;

FIG. 6 is a cross-sectional view of the system of FIG. 1 in a mixingphase;

FIG. 7 is another cross-sectional view of the system of FIG. 1 in themixing phase;

FIG. 8 is a perspective view of a mixing shaft of the mixer;

FIG. 9A is a top perspective view of a mixing paddle of the mixer;

FIG. 9B is a top perspective view of the mixing paddle in a flattenedstate;

FIG. 10 is a cross-sectional view of the mixing paddle taken generallyalong the line 10-10 in FIG. 9;

FIG. 11 is a top perspective view of a piston of the mixer;

FIG. 12 is a bottom perspective view of the piston;

FIG. 13 is a cross-sectional view of the piston taken generally alongthe line 13-13 in FIG. 11;

FIG. 14 is a top perspective view of a mixer housing of the mixer;

FIG. 15 is a bottom perspective view of the mixer housing;

FIG. 16 is a side elevational view of the mixer housing;

FIG. 17 is a top perspective view of a transfer disc of the mixer;

FIG. 18 is a bottom perspective view of the transfer disc;

FIG. 19 is a cross-sectional view of the transfer disc taken generallyalong the line 19-19 in FIG. 17;

FIG. 20 is a cross-sectional view of the system of FIG. 1 in a transferphase;

FIG. 21 is another cross-sectional view of the system of FIG. 1 in thetransfer phase;

FIG. 22 is an exploded view of a base of the mixer;

FIG. 23 is a top perspective view of the base of the mixer;

FIG. 24 is a perspective view of a transfer gear;

FIG. 25 is a perspective view of a driver;

FIG. 26 is a perspective view of a switch nut;

FIGS. 27-29 are perspective views of various spur gears;

FIG. 30 is a top perspective view of a cap of the mixer;

FIG. 31 is a bottom perspective view of the cap;

FIG. 32 is a cross-sectional view of the cap taken generally along theline 32-32 in FIG. 30;

FIG. 33 is a top perspective view of a valve ring of the mixer;

FIG. 34 is a cross-sectional view of the valve ring taken generallyalong the line 34-34 in FIG. 32;

FIGS. 35A-38B are top perspective views of alternative mixing paddles innormal and flattened states;

FIG. 39 is a top perspective view of the delivery device;

FIG. 40 is an exploded perspective view of the delivery device;

FIG. 41 is a cross-sectional view of the delivery device;

FIG. 42 is a top view of a valve housing of the delivery device;

FIG. 43 is a partial cross-sectional perspective view illustrating anoptional clutch mechanism of the delivery device;

FIG. 44 is a top perspective view of an alternative plunger of thedelivery device;

FIG. 45 is a bottom perspective view of an alternative proximal knobportion of the delivery device;

FIG. 46 is a top perspective view of the delivery device coupled to anextension tube and an enlarged luer-lock connector;

FIG. 47 is a cross-sectional view of the extension tube and the enlargedluer-lock connector;

FIG. 48 is a perspective view of a lock fitting of the extension tube;

FIG. 49 is an electrical schematic of the mixer;

FIG. 50 is a top perspective view of a motorized delivery device;

FIG. 51 is an exploded view of the motorized delivery device; and

FIG. 52 is a cross-sectional view of the motorized delivery device.

DETAILED DESCRIPTION OF THE INVENTION

For the purpose of promoting an understanding of the present invention,references are made in the text hereof to exemplary embodiments of abone cement mixing and delivery system, only some of which are depictedin the figures. It should nevertheless be understood that no limitationson the scope of the invention are thereby intended. One of ordinaryskill in the art will readily appreciate that modifications such asthose involving the materials from which the components are made, thesize of the components, functional equivalents of the elements, and theinclusion of additional elements do not depart from the spirit and scopeof the present invention. Some of these possible modifications arediscussed in the following description. Therefore, specific detailsdisclosed herein are not to be interpreted as limiting, but rather assupport for the claims and as a representative basis for teaching oneskilled in the art to employ the present invention in virtually anyappropriately detailed system, structure, or manner.

As used herein, “distal” refers to the end of the delivery device fromwhich the bone cement mixture is discharged, and “proximal” refers tothe end of the delivery device away from the end from which the bonecement mixture is discharged. The terms “substantially” and“approximately,” as used herein, may be applied to modify anyquantitative representation that could permissibly vary withoutresulting in a change in the basic function to which it is related.

Referring in more detail to the drawings, a bone cement mixing anddelivery system of the present invention is generally shown at 100 inFIG. 1. The system 100 includes a mixer 102 to mix separate componentsof bone cement to form a bone cement mixture and a delivery device 104to deliver the mixture to a target site. The target site may be ananatomical site such as a vertebral body or the target site may be in ornear an implant.

The system 100 is useful in any procedure in which bone cement or anyother mixture is required, particularly when time is a constraint andexposure of the material or its vapors to the user is to be minimized.The system 100 is capable of mixing the components and automaticallytransferring the mixture to the delivery device 104 upon completion ofmixing with no operator interaction. This reduces variability in mixingbetween users and creates consistency across multiple users. Thisautomatic transfer feature reduces time and energy otherwise spent by auser to manually mix and transfer the mixture to a delivery device suchas a conventional syringe. The system 100 also reduces exposure of theuser to the bone cement components during mixing and transfer whencompared to conventional mixing and delivery devices.

I. Mixer

Referring to FIGS. 1-3, the mixer 102 includes a base 106 for supportingthe mixer 102 on a surface. The base 106 includes rubber feet 105 forgripping the surface. A casing 107 mounts to the base 106 to cover thebase and provide an aesthetically pleasing shape to the mixer 102. Amixer housing 108 is coupled to the casing 107. A transfer conduit 110links the mixer housing 108 to the delivery device 104. The transferconduit 110 conveys the mixture from the mixer 102 to the deliverydevice 104. A switch cover 112 is pivotally mounted to the casing 107 toprotect a switch button 114 (see FIG. 4) used to begin operation of themixer 102. Once the switch button 114 is pressed, the bone cementcomponents are mixed together to form the mixture and then, once mixingis complete, the mixture is automatically transferred through thetransfer conduit 110 to the delivery device 104.

Referring to FIGS. 4 and 5, the mixer 102 is shown with the casing 107removed to expose some of its internal components. As shown, the mixer102 is battery-powered. Batteries 115 are used to power a motor 150 thatdrives the mixing and transfer operations of the mixer 102. In oneembodiment, a battery pack 109 of eight batteries 115 is used to powerthe motor 150. The motor 150 is preferably a reversible DC motor such asthose available from Mabuchi Motor Co. of Matsudo City, Japan. Possiblemodels that could be used include Model Nos. RC-280RA-2865 andRC-280SA-2865. The mixer 102 is preferably disposable such that themotor 150 and batteries 115 are selected for single use. A switch 117closes a circuit (see FIG. 49) between the batteries 115 and the motor150 to begin operation of the motor 150. The switch button 114, whenpressed, trips the switch 117 to close the circuit. Once the mixing andtransfer operations are complete, the motor 150 ceases to operate.

Referring to FIGS. 6 and 7, the base 106 of the mixer 102 comprises abottom housing portion 118 and a middle housing portion 116 secured tothe bottom housing portion 118 using conventional fasteners, adhesives,and the like. A mixing shaft 120 is rotatably supported between thehousing portions 116, 118. The mixing shaft 120 has a mixing gear 122with mixing gear teeth 123 at one end. The mixing shaft 120 is rotatablysupported in the bottom housing portion 118 by a centering pin 119. Themixing shaft 120 extends from the mixing gear end to a second end 124that is connected to a mixing paddle 126. This connection is preferablyreleasable, but could include integral or fixed connections.

Referring to FIGS. 6-10, the mixing paddle 126 includes a hub 128 withinner splines 130 that interact with outer splines 132 on the mixingshaft 120 to rotationally lock the mixing shaft 120 to the mixing paddle126 during the mixing phase (shown in FIGS. 8 and 10). The outer splines132 extend along the entire length of the mixing shaft 120 from themixing gear 122. This rotational locking feature allows the mixing shaft120 to impart rotational motion to the mixing paddle 126 to adequatelymix the bone cement components. When mixing is complete, the rotationallock between the mixing shaft 120 and the hub 128 is removed to preventfurther rotation of the mixing paddle 126 in the transfer phase.

The preferred embodiment of the mixing paddle 126 is shown in FIGS. 9A,9B, and 10. In one embodiment, the mixing paddle 126 is formed ofinjection molded plastic. In other embodiments, the mixing paddle 126 isformed from a flat piece of plastic or metal material. In theseembodiments, the mixing paddle 126 is cut from the flat piece ofmaterial and folded/shaped to the configuration shown in FIG. 9A. Themixing paddle 126 includes a flat base section 222 and a bent flap 220forming an obtuse angle with the flat base section 222. The flat basesection 222 is fixed to the hub 128 by being integrally molded with thehub 128 or by adhesive or the like. The hub 128 extends downwardly fromthe flat base section 222. The bent flap 220 is radially spaced from acenter of the hub 128. As the mixing paddle 126 rotates, the bent flap220 urges the bone cement components upwardly. A pair of flat arms 224extends upwardly from the flat base section 222 generallyperpendicularly to the flat base section 222. The flat arms 224 act asmixing vanes to mix the bone cement components.

A flat connector section 226 extends between and connects the flat arms224. The flat connector section 226 forms an obtuse angle A with theflat arms 224. As a result, when the mixing paddle 126 is urged upwardlyin the mixing chamber 138 during the transfer phase (further describedbelow), the flat connector section 226 strikes a top of the mixerhousing 108. As the mixing paddle 126 continues to move upwardly in themixing chamber 138, the mixing paddle 126 begins to compress toward aflattened configuration. This includes bending the flat arms 224downward toward the flat base section 222 about a hinge, then eventuallyflattening the flat connection section 226 and the bent flap 220 suchthat they all fall in generally the same plane as the flat base section222 (see FIG. 9B).

Referring to FIGS. 6-7 and 11-13, a piston 134 supports the mixingpaddle 126. More specifically, the hub 128 of the mixing paddle 126 isseated in a bore 136 defined through the piston 134. An o-ring seals thehub 128 in the bore 136. The piston 134 is releasably secured in themixer housing 108. Another o-ring seals the piston 134 to an interiorsurface of the mixer housing 108. The piston 134 includes a pair offlexible tabs 135 that rest beneath a shoulder 137 defined in theinterior surface of the mixer housing 108. The flexible tabs 135 holdthe piston 134 in place until such time as the piston 134 is forcedupwardly to transfer the mixture to the delivery device 104 in thetransfer phase. At that point, the flexible tabs 135 are forced inwardlyto allow the piston 134 to move upwardly along the interior surface ofthe mixer housing 108. In the mixing phase, however, the piston 134remains in place and forms a mixing chamber 138 with the mixer housing108.

In one embodiment, the mixer 102 may be shipped with a powder componentof the bone cement stored in the mixing chamber 138. In this embodiment,a cap 140 is releasably coupled to the mixer housing 108 during shipmentto keep the powder component in the mixing chamber 138. Morespecifically, the cap 140 is secured to a cylindrically-shaped top port141 of the mixer housing 108.

The top port 141 defines a pour opening 143 (see FIG. 14) that entersthe mixing chamber 138 through a plurality of web sections 145 that forma web. A plurality of port flanges 147 extends radially outwardly fromthe top port 141 to engage the cap 140. The cap 140 includes a pluralityof locking tabs 149 that engage the port flanges 147 to lock the cap 140to the mixer housing 108. An o-ring seals the cap 140 to the mixerhousing 108. When the system 100 is ready to be used, the user removesthe cap 140 to add a liquid component of the bone cement through thepour opening 143 to the powder component already placed in the mixingchamber 138 or also added through the pour opening 143. Once thecomponents are disposed in the mixing chamber 138, the mixer 102 isready for operation.

The motor 150 operates through a gear arrangement to rotate the mixingshaft 120 during the mixing phase to mix the powder and liquidcomponents. Rotation of the mixing shaft 120 imparts rotation to themixing paddle 126, which is disposed in the mixing chamber 138. The geararrangement includes a face gear 152 having a set of face gear teeth154. A pinion gear 156 (see FIG. 22) is fixed to a shaft of the motor150 to rotate with the motor 150 during operation. The pinion gear 156has pinion gear teeth 157 engaging the face gear teeth 154 such that themotor 150 drives the face gear 152 during operation.

The face gear 152 drives a first spur gear 160, which drives a secondspur gear 166. More specifically, the face gear 152 has a lower set ofgear teeth 154 continuously engaging an upper set of spur gear teeth 162formed on the first spur gear 160. A lower set of spur gear teeth 164formed on the first spur gear 160 continuously engages an upper set ofspur gear teeth 168 formed on the second spur gear 166. The upper set ofspur gear teeth 168 engages the mixing gear teeth 123 to rotate themixing shaft 120 and mixing paddle 126 during the mixing phase.

The second spur gear 166 drives a third spur gear 167. In particular, alower set of spur gear teeth 170 formed on the second spur gear 166engages a lower set of spur gear teeth 169 formed on the third spur gear167. The third spur gear 167 also includes an upper set of spur gearteeth 171 (see FIG. 7). The upper set of spur gear teeth 171 formed onthe third spur gear 167 engages a set of transfer gear teeth 176 formedon a transfer gear 172. As a result, when the motor 150 operates, boththe mixing shaft 120 and the transfer gear 172 rotate. Each of the facegear 152 and spur gears 160, 166, 167 are supported by centering pinscaptured between the middle housing portion 116 and the bottom housingportion 118.

The transfer gear 172 is generally cylindrical and includes a first openend and a second, partially closed, end defining an aperture. The mixingshaft 120 is rotatably supported in the aperture such that rotation ofthe mixing shaft 120 does not interfere with rotation of the transfergear 172. The speed with which the mixing shaft 120 and transfer gear172 rotate depends on the gear ratios of the gears. In some embodiments,the gear ratios are set such that the transfer gear 172 rotates slowerthan the mixing shaft 120.

The transfer gear 172 forms part of a transfer mechanism of the mixer102. The transfer mechanism transfers the mixture out from the mixingchamber 138 and into a delivery chamber of the delivery device 104 aftermixing. Transfer threads 178 are defined on an outer surface of thetransfer gear 172. A switch nut 180 is threaded on the outer surface ofthe transfer gear 172. The switch nut 180 is fixed from rotation so thatas the transfer gear 172 rotates, the switch nut 180 moves along theouter surface of the transfer gear 172. The switch nut 180 has twoprojections 182 with a notch 184 defined therebetween. The notch 184rides along an edge of a printed circuit board 186 fixed to the bottomhousing 118 to prevent rotation of the switch nut 180 with the transfergear 172. In other words, the edge of the printed circuit board 186rides in the notch 184 between the projections 182 as the transfer gear172 rotates thereby preventing the switch nut 180 from rotating. Themotor 150, by way of its rotation of the transfer gear 172, operativelyengages the switch nut 180. This is best shown in FIG. 5.

During operation, after the switch 117 has been closed, the switch nut180 rides along the printed circuit board 186 as it further threads ontothe transfer gear 172 in one direction until it engages a second switch190 (see FIG. 5), spaced from the switch 117. Thus, the switch nut 180acts as a switch actuator 180. Other suitable actuators could beemployed. The second switch 190, when tripped by movement of the switchnut 180, opens the circuit between the batteries 115 and the motor 150to shut down operation of the motor 150 (see FIG. 49).

The transfer mechanism further includes a driver 192 that is keyed tothe transfer gear 172 to rotate with the transfer gear 172. Thus, thetransfer gear 172 operatively couples the motor 150 to the driver 192.The driver 192 includes keyways 193 (see FIG. 22), while the transfergear 172 includes keys 195 (see FIG. 22) slidably disposed in thekeyways 193. In other embodiments, the driver 192 could include the keys195, while the transfer gear 172 includes the keyways 193. Of course,other coupling mechanisms could be used to lock rotation of the transfergear 172 to the driver 192. The driver 192 is free to move axiallyrelative to the transfer gear 172. The driver 192 has driving threads194 defined on its outer surface. During the mixing phase, the drivingthreads 194 are rotatably received in a bore 196 of a transfer disc 198.The transfer disc 198 is coupled to a bottom of the mixer housing 108and fixed from movement. The transfer disc 198 also forms part of thetransfer mechanism and acts as a drive nut 198 for the driver 192.

During the mixing phase, the driving threads 194 rotate within the bore196 of the transfer disc 198 and engage corresponding threads 202 in thebore 196. Thus, the transfer disc 198 operates as a fixed drive nut.FIGS. 6 and 7 show the driving threads 194 fully advanced through thebore 196. This represents the end of the mixing phase. A spring 203biases the driver 192 upwardly in the cavity of the transfer gear 172 tofacilitate engagement with the threads 202. The time required for thedriving threads 194 to fully advance through the bore 196 represents themixing phase. In other words, a predetermined mixing period is set bythe amount of time it takes for the driving threads 194 to fully advancethrough the transfer disc 198. Once the driving threads 194 completelypass through the bore 196, the transfer phase begins. The transfer phasecontinues for a predetermined transfer period, which is defined betweenthe start of transfer and the actuation of the second switch 190, whichceases operation of the motor 150.

Referring to FIGS. 20 and 21, when the driver 192 advances in thetransfer phase, it pushes the push cap 200 axially upwardly against thepiston 134, which in turn urges the piston 134 upwardly to move throughthe mixing chamber 138. The piston 134 is sealed to the wall of themixer housing 108 and includes a face that contacts the mixture in themixing chamber 138. The mixture is pushed upwardly through an exit port204 (also referred to as a transfer port 204; see FIG. 21) into thetransfer conduit 110 and then into the delivery device 104. For thisreason, the piston 134 is also considered part of the transfer mechanismof the mixer 102.

As the driver 192 advances in the transfer phase and moves the piston134 through the mixing chamber 138, the driver 192/piston 134 disengagesthe mixing paddle 126 from the mixing shaft 120. More specifically, thehub 128 with inner splines 130 is lifted off the outer splines 132 onthe mixing shaft 120 to rotationally unlock the mixing shaft 120 fromthe mixing paddle 126 during the transfer phase. The mixing shaft 120 isheld down by the transfer gear 172 while the mixing paddle 126 isdisengaged from the mixing shaft 120. As the piston 134 rises in themixing chamber 138, the mixing paddle 126 folds down to a compact sizeto permit a majority of the mixture to be pressed out of the mixingchamber 138 and into the delivery device 104.

The motor 150 operates through the gear arrangement to rotate the mixingshaft 120 and actuate the mixing paddle 126 during the mixing phase tomix the powder and liquid components, while also rotating the transfergear 172 to actuate the transfer mechanism to automatically transfer themixture from the mixing chamber 138 to the delivery chamber of thedelivery device 104 after the predetermined mixing period has elapsed.In other words, the motor 150 operatively engages both the mixing shaft120 and the transfer mechanism (including the transfer gear 172, driver192, piston 134, etc.). The motor 150 continues operation from itsstart, upon actuation of the switch 117, until it stops upon actuationof the second switch 190, during which time the motor 150 operates tomix the components in the mixer 102 and transfer the mixture to thedelivery device 104. In one embodiment, the switch 117 and the secondswitch 190 are combined into a single switch (not shown) that is closedto start operation of the motor 150 by an actuator, and opened to stopoperation of the motor 150.

In still other embodiments, the second switch 190 reverses the polarityof the motor 150 and causes the transfer gear 172 to reverse itsrotation. Consequently, the switch nut 180 changes direction and ridesback along the printed circuit board 186. In this embodiment, thethreads 202 are configured such that during the mixing phase the drivingthreads 194 cannot engage the threads 202 of the transfer disc 198.However, when the polarity switch 190 is tripped by the switch nut 180,the driver 192 reverses its direction of rotation with the transfer gear172 and engages the threads 202 in a manner that advances the driver 192axially during the transfer phase. In this embodiment, a third switch(not shown) or other mechanism would be required to be tripped by theswitch nut 180 as it travels back along the printed circuit board 186 tostop operation of the motor 150.

As shown in FIGS. 7 and 14-19, the bottom of the mixer housing 108includes a flange 173 and a short wall 175 extending downwardly from theflange 173. A plurality of locking tabs 177 (see FIG. 15) are spacedcircumferentially about the short wall 175 and extend radially outwardlyfrom the short wall 175. During assembly of the mixer 102, the lockingtabs 177 are inserted into openings 179 (see FIG. 17) defined in a topof the transfer disc 198. The casing 107 is captured between the mixerhousing 108 and the transfer disc 198 when this is done (see FIG. 21).The mixer housing 108 is then rotated one-quarter turn such that thelocking tabs 177 slide beneath corresponding locking members 183 on thetransfer disc 198 until they reach stops 199. The piston 134 rests ontop of the transfer disc 198 and is initially coupled to the transferdisc 198 by the push cap 200.

FIG. 22 illustrates an exploded view of the base 106 including thebottom housing portion 118, the middle housing portion 116, and the geararrangement disposed therebetween for converting motor operation intomixing and transfer operations. FIG. 23 shows the base 106 fullyassembled.

FIGS. 24-29 illustrate perspective views of the transfer gear 172, thedriver 192, the switch nut 180, the first spur gear 160, the second spurgear 166, and the third spur gear 167.

Referring to FIGS. 30-32, the cap 140 is shown. The cap 140 includes atop 232. A cap wall 234 is disposed on the top 232 and extendsdownwardly from the top 232 to a bottom wall 236. A gripping flange 238extends downwardly from the top 232 and is spaced from the cap wall 234.A plurality of locking tabs 240 are disposed on the gripping flange 238and extend radially inwardly into a gap between the gripping flange 238and the cap wall 234. The locking tabs 240 engage the tabs 147 on thetop port 141.

Referring to FIGS. 7, 33, and 34, a valve 206 is arranged in the exitport 204 to prevent the escape of unmixed components during mixing.Referring to FIG. 34, the valve includes a plastic or metal ring 210having a plurality of apertures 212 for receiving an elastomericmaterial 213 in a molding process. The material 213 fills in theapertures 212 as shown in FIG. 34 and includes cross-cut slits 214 thatremain closed in the mixing phase, but open up and allow the mixture toflow therethrough into the transfer conduit 110 during the transferphase.

II. Alternative Mixing Paddles

Alternative embodiments of the mixing paddle 126 are shown in FIGS.35A-38B. In FIGS. 35A and 35B, the mixing paddle 126′ is formed ofplastic and includes a pair of flat arms 224′ extending upwardly from aflat base section 222′. A pair of opposed bent flaps 220′ form an obtuseangle with the flat base section 222′. In this embodiment, the flat arms224′ are opposed from one another on opposite sides of a center of themixing paddle 126′. The flat arms 224′ further include bent ends 225′that strike the top of the mixer housing 208 in the transfer phase andbend inwardly to flatten the flat arms 224′.

Referring to FIGS. 36A and 36B, the mixing paddle 126′ is formed ofmetal such as stainless steel or aluminum.

In FIGS. 37A and 37B, a mixing paddle 126″ has a pair of opposed arms224″ that are pivotally connected to a flat base section 222″ by a pairof pivot pins 229.

In FIGS. 38A and 38B, a mixing paddle 126′″ includes a flat base section222′″, a bent flap 220′″ forming an obtuse angle with the flat basesection 222′″, and a single flat arm 224′″ extending upwardly generallyperpendicularly to the flat base section 222′″. An extension 231 extendsat an obtuse angle for crossing the mixing chamber 138. In each of theembodiments of the alternative mixing paddles, the arms 224′, 224″,224′″ are configured to be supported by the wall of the mixer housing108 during rotation in the clockwise direction (when viewed from above),but unsupported when rotating in the counterclockwise direction. Whenunsupported, they are urged into their compressed state. This is usefulwhen the motor 150 changes direction during the transfer phase, asdescribed in the alternative transfer embodiment above.

The mixer housing 108, transfer disc 198, mixing shaft 120, transfergear 172, face gear 152, spur gears 160, 166, 167, switch nut 180,driver 192, piston 134, cap 140, mixing paddle 126, bottom housingportion 118, middle housing portion 116, casing 107, and switch cover112 are preferably formed of a bio-compatible plastic material such asnylon, PBT (polybutylene terephthalate), PC (polycarbonate), ABS(acrylonitrile butadiene styrene), glass-filled nylon, glass-filledpolyetherimide, or the like.

III. Delivery Device

Referring to FIGS. 39-42, the delivery device 104 is shown. The deliverydevice 104 comprises a reservoir 302 defining the delivery chamber forreceiving the bone cement mixture from the transfer conduit 110 duringthe transfer phase. The reservoir 302 includes an entry port 314 (orinlet port 314) defined in a sidewall of the reservoir 302. A valvehousing 316 (see also FIG. 42) is outfitted with an o-ring 318 and isseated in the entry port 314. The valve housing includes a plurality offlow paths 319 and a central bore 321. As shown in FIG. 41, a one-wayumbrella valve 320 is supported in the central bore 321 of the valvehousing 316 such that the bone cement mixture opens the valve 320 tofill the reservoir 302. The one-way umbrella valve 320 prevents the bonecement mixture from re-entering the mixer 102 during the transfer phase.A handle 304 is mounted about the reservoir 302 for grasping by theuser.

A rotatable fitting 322 is secured in the valve housing 316 during themixing and delivery phases. To accomplish this, the rotatable fitting322 fits through an aperture 325 in the handle 304. The rotatablyfitting 322 includes a pair of diametrically opposed locking tabs 306that engages the handle 304. The handle 304 includes a plurality oflocking flanges 327 spaced circumferentially from one another in theaperture 325. The locking flanges 327 extend radially inwardly into theaperture 325. During assembly, the locking tabs 306 pass into theaperture 325 between the locking flanges 327 and are rotated into placewith the locking tabs 306 disposed beneath the locking flanges 327. Anannular flange 329 of the rotatable fitting 322 rests on top of thelocking flanges 327 when in position (see FIG. 41).

One end of the transfer conduit 110 fits into the rotatable fitting 322.A through bore 331 is defined through the rotatable fitting 322 totransfer the bone cement mixture to the reservoir 302 from the transferconduit 110. During transfer the bone cement mixture passes through thethrough bore 331 under pressure thereby opening the one-way umbrellavalve 320 and passing through the flow paths 319 (see FIG. 42) into thereservoir 302. Once transfer is complete, the rotatable fitting 322 isrotated counterclockwise to release the rotatable fitting 322 from thevalve housing 316 thereby allowing the user to remove the deliverydevice 104 from its cradle mounts 333 on the mixer 102 in preparationfor delivering the bone cement mixture to the target site.

A nut 324 is mounted to a proximal end of the reservoir 302. Inparticular, the proximal end of the reservoir 302 has a rectangularflange 326 for supporting the nut 324. The rectangular flange 326 slidesinto a slot 328 defined in the nut 324. The nut 324 has a generallybox-like shape that is secured between two halves 330, 332 of the handle304. Each half 330, 332 of the handle 304 has a complimentary box-shapedcavity 334 such that the nut 324 fits snugly in the cavities 334 whenthe halves 330, 332 are fixed together. The halves 330, 332 may be fixedtogether by conventional fasteners, adhesives, and the like.

A plunger 310 drives the mixture through the delivery chamber of thereservoir 302 during delivery. The plunger 310 includes a threaded shaft336 that engages threads 338 of the nut 324. A plunger head 344 issnap-fit to the threaded shaft 336 to form a distal end of the plunger310. The plunger head 344 is snap-fit to the threaded shaft 336 byinserting a stem 346 of the plunger head 344 into a bore 348 definedthrough the threaded shaft 336. Referring to FIGS. 40 and 41, the stem346 has a pair of diametrically opposed detent ramps 354 that slidethrough the bore 348 in a compressed configuration (by being pressedtogether via a slot 349 defined through the stem 346) until the ramps354 pass a shoulder 356 in the bore 348. Once they pass the shoulder356, the ramps 354 spring outwardly to engage the shoulder 356 andprevent withdrawal of the plunger head 344. An o-ring 350 is seated witha dynamic seal 351 in an outer groove defined in the plunger head 344 toseal against an interior of the reservoir 302.

A proximal end 311 of the plunger 310 has a generally box-like shape. Aknob 312 is mounted about the proximal end 311 of the plunger 310 tofacilitate rotation of the plunger 310. The knob 312 has a proximal knobportion 340 defining a box-shaped cavity 341 for receiving the proximalend 311 of the plunger 310 such that as the user rotates the proximalknob portion 340, the plunger 310 also rotates. A distal knob portion342 is fastened to the proximal knob portion 340 using fasteners,adhesives, or the like. The proximal end 311 of the plunger 310 iscaptured between the proximal 340 and distal 342 knob portions toprevent the proximal end 311 of the plunger 310 from slipping out of thebox-shaped cavity 341.

IV. Alternative Delivery Device with Clutch

Referring to FIGS. 43-45, an alternative plunger shaft 360 is shown.Referring specifically to FIG. 44, a proximal end of the plunger shaft360 includes a flange 362 and a plurality of projections 364 disposed onthe flange 362. The plurality of projections 364 extend proximally fromthe flange 362. The projections 364 are circumferentially spaced fromone another about a periphery of the flange 362. Each of the projections364 has a vertical surface 366 and an angled surface 368 (forms acuteangle with flange 362) meeting at a plateau 370 generally parallel tothe flange 362. In the embodiment, a knob 371 is mounted to the proximalend of the plunger shaft 360 to facilitate rotation of the plunger shaft360. The knob 371 includes a proximal knob portion 372. The proximalknob portion 372 includes a top 374 and a plurality of complimentaryprojections 376 disposed on the top 374 and extending distally from thetop 374. The complimentary projections 376 mate with the projections 364on the flange 362 by fitting in spaces defined between the projections364 on the flange 362.

Each of the complimentary projections 376 also includes a verticalsurface 378 and an angled surface 380 meeting at a plateau 382 generallyparallel to the top 374. A distal knob portion 384 is fastened to theproximal knob portion 372 using fasteners, adhesives, or the like. Theproximal end of the plunger shaft 360 is captured between the proximal372 and distal 384 knob portions. The plunger shaft 360 passes through abore 385 defined through the distal knob portion 384. A spring 386 restson a shoulder 388 defined in the distal knob portion 384 about the bore385. The spring 386 acts between the shoulder 388 and the flange 362.

The spring 386, along with the projections 364, 376, form a clutchmechanism. This clutch mechanism can be configured to slip whenundesired pressures are reached in the delivery device 104. During use,when a user is rotating the knob 371, the projections 376 formed on theproximal knob portion 372 engage the projections 364 formed on theflange 362 of the plunger shaft 360. In particular, the angled surfaces368, 380 engage one another as the user rotates the knob 371 clockwise.The spring 386 acts to keep the angled surfaces 368, 380 in engagementduring normal operation. However, when undesired pressures are reachedthe angled surfaces 368, 380 begin to slip and the flange 362 separatesfrom the proximal knob portion 372. As a result, the projections 364,376 slide out of engagement thereby preventing further advancement ofthe plunger shaft 360 until pressure is normalized. Different springconstants can be used to alter the pressure at which the clutchmechanism is actuated. Furthermore, the projections 364, 376 could beoriented radially, as opposed to axially, such that axial forcessupplied by the user does not affect the clutch mechanism's operation.

V. Extension Tube with Enlarged Connector

Referring to FIG. 46, an extension tube 400 is shown mounted to thedistal end of the reservoir 302. In one embodiment, the extension tube400 is automatically primed with bone cement during the transfer phase.In other words, the system 100 is designed for use with specifiedmixture volumes that fill both the reservoir 302 and the extension tube400 in the transfer phase. This eliminates the need for the user toprime the extension tube 400 manually.

Referring to FIGS. 47 and 48, the extension tube 400 includes a tubefitting 402 for securing the extension tube 400 to the delivery port 306of the reservoir 302. Referring back to FIG. 39, the delivery port 306includes a pair of diametrically opposed projections 404 and the tubefitting 402 includes a pair of diametrically opposed channels 406 forreceiving the projections 404 when the tube fitting 402 is axiallymounted onto the discharge port 306. Once the projections 404 bottom-outin the channels 406, the tube fitting 402 is rotated. The projections404 then ride in diametrically opposed slots 408 defined through thetube fitting 402. The tube fitting 402 is then prevented from axiallysliding off the delivery port 306. In other embodiments, the tubefitting 402 is fixed to the delivery port 306 with adhesive, press fit,welding, or the like.

Referring to FIG. 47, an enlarged luer-lock connector 410 is mounted toa distal end of the extension tube 400. The luer-lock connector 410comprises a knob 412, a spindle 414, and a collar 416. The collar 416includes a side port 418 defining a side bore 426. A main bore 420 isdefined through the collar 416 normal to the side port 418. The distalend of the extension tube 400 fits into the side bore 426 of the sideport 418. The extension tube 400 may be fixed in the side port 418 bypress fit, ultrasonic welding, adhesive, or the like.

The spindle 414 is rotatably supported in the main bore 420 of thecollar 416. A pair of o-rings 415 seals the spindle 414 in the main bore420. The spindle 414 includes a through bore 422 and a cross bore 424aligned with the side bore 426 in the side port 418. The cross bore 424is disposed between the o-rings 415. The knob 412 includes a stem 428that fits into the through bore 422 in a top of the spindle 414. Thestem 428 is fixed in the through bore 422 by a press-fit, ultrasonicwelding, adhesive, or the like.

The knob 412 further includes a grasping portion 430 shaped for graspingby a hand of the user. The spindle 414 fits inside an annular cavity 432in the knob 412. A bottom of the spindle 414 has a connector portion434, e.g., a standard luer-lock fitting 434. The through bore 422continues through the luer-lock fitting 434. The luer-lock fitting 434is configured for attaching to a corresponding luer-lock fitting 436 ona delivery cannula 440. During use, the user grasps the grasping portion430 of the knob 412 and rotates the knob 412 and spindle 414 to lock theluer-lock fitting 434 of the spindle 414 on the luer-lock fitting 436 onthe delivery cannula 440. The oversized grasping portion 430 facilitateseasier connection of the extension tube 400 to the delivery cannula 440to deliver the bone cement mixture through the extension tube 400, thethrough bore 422, the delivery cannula 440, and to the target site.

The reservoir 302, rotatable fitting 322, handle 304, knob 312, plunger310, nut 324, valve housing 316, tube fitting 402, and enlargedluer-lock connector 410 are preferably formed of a bio-compatibleplastic material such as nylon, PBT (polybutylene terephthalate), PC(polycarbonate), ABS (acrylonitrile butadiene styrene), glass-fillednylon, glass-filled polyetherimide, or the like. The umbrella valve 320is preferably formed of nitrile.

VI. Alternative Delivery Device with Delivery Motor

Referring to FIGS. 50-52, an alternative delivery device 504 is shown.The delivery device 500 comprises a reservoir 502 defining a deliverychamber for receiving the bone cement mixture from the transfer conduit110 during the transfer phase. The reservoir 502 threadably engages acap 505 seated in an end plate 507. The end plate 507 is supportedbetween and fixed to two side plates 509. The end plate 507 has aU-shaped cutout portion into which the cap 505 extends. The cutoutportion supports the cap 505. A bottom plate 506 supports and is fixedto the side plates 509. A middle plate 513 is fixed to the bottom plate506 and the two side plates 509. The middle plate 513 is preferablyrectangular in shape to prevent rotation of the middle plate 513 betweenthe side plates 509. A nut 524 is disposed between the middle plate 513and the cap 505. The nut 524 is fixed from rotation relative to theplates 507, 509, 513 by being fixed to the middle plate 513 by adhesive,welding, fasteners, or the like.

Referring to FIGS. 51 and 52, a plunger 510 drives the mixture throughthe delivery chamber of the reservoir 502 during delivery. The plunger510 includes a threaded shaft 536 that engages threads (not shown) ofthe nut 524. A plunger head 544 is fixed to the threaded shaft 536 toform a distal end of the plunger 510. An o-ring 550 with a dynamic seal551 is seated in an outer groove defined in the plunger head 544 to sealagainst an interior of the reservoir 502.

A proximal end 511 of the plunger 510 is slidably disposed in a rotatingdrive shaft 600. The drive shaft 600 is hollow and includes a key 602disposed along its internal surface. The key 602 protrudes radiallyinwardly. The plunger 510 includes a keyway 604 disposed in an outersurface of the threaded shaft 536. The key 602 is configured to slide inthe keyway 604 as the drive shaft 600 rotates due the fixed nature ofthe nut 524.

Referring to FIG. 52, a delivery motor 606 and gear box 608 operate torotate the drive shaft 600. The gear box 608 includes a box 610 and acover 612. The delivery motor 606 is supported in a mounting sleeve 614disposed on the cover 612. A motor shaft 616 penetrates through thecover 612 into the gear box 608. A pinion gear 616 is fixed to the motorshaft 616 to rotate with the delivery motor 606 during its operation. Aseries of spur gears 618, 620, 622, 624 are rotatably supported byshafts 626, 628. The shafts 626, 628 are fixed to the box 610 and cover612 for support.

A proximal end of the drive shaft 600 is rotatably supported in the box610 by a bushing 630. A drive gear 632 is fixed to the proximal end ofthe drive shaft 600 and rotatably supported by a shaft 634. The shaft634 is fixed to the cover 612. The series of spur gears 618, 620, 622,624 transfer power from the motor shaft 616 to the drive gear 632 duringoperation. A switch 640 controls operation of the delivery motor 606.The delivery motor 606 may be powered by a battery pack 607. After themixture has been transferred from the mixing chamber 138 to the deliverychamber of the reservoir 502, as described above, the user can operatethe delivery motor 606 to delivery the mixture to the target site.

VII. Drool Valve and Viscosity Meter

Referring back to FIG. 50, a drool valve 700 may be positioned at anypoint along the extension tube 400, including at the distal end of theextension tube 400. The drool valve 700 may be a motor-controlled valveor a solenoid valve. The drool valve 700 is controlled by a controller702. The controller 702, in this embodiment, also controls the deliverymotor 606 through the switch 640. The drool valve 700 operates todiscontinue flow of the mixture through the extension tube 400 from thedelivery device 500 upon actuation of the delivery switch 640 therebypreventing excess mixture from entering the target site. Without thedrool valve 700, when the user actuates the delivery switch 640 to stopoperation of the delivery motor 606, there is still pressure in theextension tube 400 due to the compressible nature of the mixture. Thispressure tends to deliver an additional amount of the mixture to thetarget site after the user desires to stop flow of the mixture. With thedrool valve 700, the amount of the mixture delivered can be bettercontrolled.

In operation, the user actuates the switch 640 to send power to thedrool valve 700 and the delivery motor 606. This opens the drool valve700 and starts operation of the delivery motor 606. Operation of thedelivery motor 606 rotates the drive shaft 600 and advances the plunger510 in the reservoir 502 to begin delivering the mixture from thereservoir 502, down the extension tube 400, to the target site. When theuser wishes to stop the flow of the mixture, the switch 640 is againactuated to signal the controller 702 that the delivery motor 606 is tobe stopped and the drool valve 700 is to be closed. The controller 702then discontinues power to the delivery motor 606 and the drool valve700.

A viscosity meter 710 monitors current draw on the delivery motor 606 toapproximate the viscosity of the mixture in the reservoir 502. Theviscosity meter 710 can be a current meter integrated into thecontroller 702 to monitor the current draw from the delivery motor 606.The controller 702 then correlates current draw to viscosity by way of alook-up table using correlation values that can be easily derived. Adisplay 712 then displays the approximate viscosity of the mixture. Ofcourse, the viscosity measurement is an estimate and not an exactmeasurement of viscosity, but can be useful in determining how muchlonger the working time window for the particular bone cement being usedwill remain open.

While this description is directed to a few particular embodiments, itis understood that those skilled in the art may conceive ofmodifications and/or variations to the specific embodiments shown anddescribed herein. Any such modifications or variations that fall withinthe purview of this description are intended to be included herein aswell. It is understood that the description herein is intended to beillustrative only and is not intended to be limited.

1. A bone cement mixing and delivery system, said system comprising: amixer including: a shell, said shell defining a mixing chamber forreceiving bone cement-forming components, the shell having a dischargeport that opens out of the mixing chamber; and a piston disposed in saidshell and having a face directed towards the shell mixing chamber, saidpiston being moveable mounted to said shell to move through the mixingchamber so as to push the cement out through the shell discharge port; adelivery device, said delivery device having: a tube that defines areservoir, said tube having a distal end opening, a proximal end openingand an entry port into the reservoir, the entry port being separate fromthe distal and proximal end openings, said entry port being in fluidcommunication with said mixer shell discharge port; and a plungermounted to tube that extends from the proximal opening of said tube,said plunger configured to slide toward the distal opening to pushcement out of the distal opening; a flexible extension tube that extendsforward from the delivery tube distal opening, said extension tubehaving a longitudinal axis and a lumen that extends along thelongitudinal axis, the lumen opening at the distal end of said tube; anda connector, said connector mounted to the distal end of said extensiontube, said connector including: a housing, said housing being attachedto the distal end of said extension tube and having a main bore intowhich the extension tube distal end lumen opens, the main bore beingangularly offset from the longitudinal axis of said extension tube; aspindle rotatably seated within the main bore of said housing, saidspindle having a fitting configured for removably receiving a deliverycannula that is configured for insertion into living tissue, a bore inselective fluid communication with the lumen of said extension tubewherein the spindle bore extends to the cannula, said spindle furtherbeing shaped to rotate between a closed position in which said spindleblocks flow from the extension tube into the spindle bore, and an openposition in which spindle allows flow from the extension tube into thespindle bore so that the cement can flow into the cannula; and a knobattached to said spindle for rotating said spindle between the closedand open positions, said knob having a grasping portion, wherein saidknob grasping portion extends radially outwardly beyond said housing. 2.The bone cement mixing and delivery system of claim 1, wherein saidspindle includes opposed first and second ends where said knob islocated at the first end, and said fitting located at the second end. 3.The bone cement mixing and delivery system of claim 1, wherein saiddelivery system further includes a tube fitting, said tube fittingconnecting a proximal end of said extension tube with the distal endopening of said delivery device tube so that extension tube is in fluidcommunication with said delivery tube.
 4. The bone cement mixing anddelivery system of claim 1, wherein said spindle is sealed within themain bore of said housing a pair of O-rings.
 5. The bone cement mixingand delivery system of claim 1, wherein said housing is further formedto include a side port that extends outwardly from said housing, saidside port having a side bore wherein said side bore is in registrationwith the lumen opening at the distal end of said extension tube.
 6. Thebone cement mixing and delivery system of claim 1, wherein said spindlefitting is orthogonal to the longitudinal axis of said extension tube.7. The bone cement mixing and delivery system of claim 1, wherein saidmixer includes an electrically actuated drive assembly disposed in abase that is connected to: a paddle to move said paddle in the mixingchamber, and said piston to move said piston through the mixing chamber.